Sale ends April 30th for Synth V software, May 9th, for Cevio & Vocaloid software. Some vocal synths also have extra point back campaigns as well. (Purchases thru the bolded links help financially support this blog, the list below is only a small sample size of the voicebanks on sale!)
For new users of DLSite, be sure to switch the website page to English and you will get a 30% off coupon on the top banner of the website. This coupon can be combined with sale prices, netting you some vocal synths at a very good price!